U.S. Pat. Nos. 4,963,995 and 5,057,932 to Lang teach the transmission of audio/video program information in a burst period of time that is substantially less than the time required for real time viewing of that audio/video program information. These prior art references teach the general aspects of compression, storage, burst transmission, reception, decompression, and display of audio/video program information. However, they do not address the specific aspects of a burst transmission system for cyclic distribution of audio/video program information. Cyclic distribution, as used herein, is directed to a method of transmitting audio/video program information that is commonly referred to as pay-per-view (PPV).
In a conventional PPV system, the subscriber selects an audio/video program, such as a movie, from a predetermined broadcast schedule. This ordering process can take place in many ways, such as calling a specified telephone number from a touch-tone telephone, pressing the appropriate keys on the cable converter box that is supplied by the service provider, speaking directly with an operator over a telephone, etc. In any case, the subscriber always selects a program from a predetermined schedule of programs that the service provider will be broadcasting in real time. When an order is placed, the cable converter box will automatically unscramble the program on the selected television channel so that the subscriber may view the program as it is being broadcast.
Video-on-demand (VOD) systems differ from PPV systems in that the subscriber may order any audio/video program from a list of available titles in an audio/video library. The selected audio/video program may be transmitted or otherwise distributed in whole or in part to the subscriber in a number of ways, including the less than real time burst transmission described by Lang. Regardless of the chosen transmission medium, the subscriber selects any available audio/video program for viewing or delivery, as opposed to tuning in to a broadcast that is on a predetermined schedule over which the subscriber has no control.
The present invention is directed at bridging the gap between PPV and VOD systems of the prior art. As in the VOD systems described in the prior art patents cited above, burst transmissions are utilized as the preferred distribution means. However, instead of providing an audio/video library that permits the subscriber to select any program for delivery, the present invention combines the predetermined, cyclic schedules of conventional PPV systems with the burst transmission technique taught by Lang. This combination results in simplified and lower cost video library equipment. It also results in a greatly enhanced PPV system from the subscriber's viewpoint. In a conventional PPV system, the audio/video programs are broadcast over coaxial cable, microwave, fiber optics or any of a variety of transmission systems in real time. That is, the programs are broadcast or literally played back in real time to the subscribers of such systems. Thus, it is not possible for the viewer to exercise VCR-type control during the playback, such as stop, pause, rewind or fast-forward. In providing an audio/video program broadcast schedule characteristic of conventional PPV systems, but using the burst transmission technique taught by Lang, the present invention provides enhanced user functionality over conventional PPV systems at a much lower cost than is associated with library-based VOD systems.
The apparatus of the present invention includes a central library storing a mulitplicity of time compressed digital audio/video programs that may be selectively transmitted in a burst time period to corresponding storage at one or more remote subscriber locations, where the transmitted program may be decompressed and viewed in accordance with the teachings of Lang. The central library provides cyclic, predetermined broadcast transmission of the time-compressed digital audio/video programs stored therein. A receiver at each of the remote subscriber locations continuously monitors a communications channel over which the sequential stream of time-compressed audio/video programs is broadcast from the central library, but is operative for storing only the program or programs that have been ordered by a subscriber.